Remove command-center page and dependencies

The /admin/command-center route was platform_admin-only, used a heavy
custom theme (Major Mono / JetBrains / Inter Tight + ~700 lines of
schematic CSS), called three RPCs, and overlapped with the per-brand
dashboards reachable at /admin, /admin/orders, /admin/stops, and
/admin/reports. The page is being removed; it didn't justify the
build complexity, font payload, or schema surface area.

Changes:
- Drop page, dashboard component, CSS, and server actions
- Remove the platform_admin nav entry from header + sidebar
- Remove the cmd+K palette entry
- Add migration 0042 to drop the 3 RPCs, founder_pain_log table,
  and founder_pain_log_platform view it owned
- Decrement route count in docs/pricing-assessment.md (88 -> 87)

Verification: tsc clean, eslint clean, npm run build clean, command-
center absent from the route list.

src/components/admin/AdminSidebar.tsx

@@ -12,7 +12,6 @@ import {
   Ship,
   Mail,
   Store,
-  Sparkles,
   Upload,
   BrainCircuit,
   Clock,
@@ -74,12 +73,6 @@ const NAV_GROUPS: NavGroup[] = [
     label: "Workspace",
     items: [
       { href: "/admin", label: "Dashboard", icon: LayoutDashboard },
-      {
-        href: "/admin/command-center",
-        label: "Command Center",
-        icon: Sparkles,
-        requiresPlatformAdmin: true,
-      },
     ],
   },
   {